The invention described herein is designed to solve a common problem faced in building construction; namely, the placement of electrical boxes containing electrical or electronic devices such as duplex receptacles, switches or media plugs into mandated fire walls in commercial buildings. Local, state, and national fire codes place constraints on where such boxes can be located and the ASTM E-119 vertical wall test is used to test the resilience of these firewalls against direct heat, smoke, and gases. What is needed is a quickly and easily retrofittable fire safety device that will allow new and already-existing electrical boxes in firewalls to pass the ASTM E-119 one- and two-hour fire tests.